Ridiculously low Compression Test.. Help

[ebb3ka94]

So I did a compression test just now. Engine was hot enough to where the spark plugs were to hot to hold. Didnt do WOT though but that wouldnt give me such stupid low numbers as..?

1: 56
2: 62
3: 53
4: 70

Engine is a Stage 1 short block from SIM racing with 800 miles.. ummm help :'(

 

[Dsmkauai]

Holy crap that's low bro sorry to see that. Was the motor properly broken in? Did you do a wet test yet to see what numbers come up? Did anything happen before to make you check compression? Did you check timing?

 

[ebb3ka94]

Holy crap that's low bro sorry to see that. Was the motor properly broken in? Did you do a wet test yet to see what numbers come up? Did anything happen before to make you check compression? Did you check timing?

Yes, no, oil in coolant and oil coming from valve cover (new gasket and bolts tight) dip stick being forced out.

 

[donniekak]

Unless all the plugs were out at once, and the throttle was wide open, the numbers are meaningless.

 

[ebb3ka94]

Unless all the plugs were out at once, and the throttle was wide open, the numbers are meaningless.

All the plugs were out and even if i didnt have WOT it should have built up to, lets say at least 150

 

[Dsmkauai]

So if you have oil in the coolant the headgasket is definitely blown bro. Time to pull the head and upgrade something's while your in there. let us know if you need any help

Having the throttle WOT just helps the test build faster, you can still get good results with it closed and if you have plugs in other cylinders its just better to do the test with all the plugs out and WOT.

 

[DSMnoobsause]

That engine would not run with those numbers. I would try another guage.

 

[ebb3ka94]

So if you have oil in the coolant the headgasket is definitely blown bro. Time to pull the head and upgrade something's while your in there. let us know if you need any help

Having the throttle WOT just helps the test build faster, you can still get good results with it closed and if you have plugs in other cylinders its just better to do the test with all the plugs out and WOT.

Well it seems I do have blow by tho. Unless the oil its just happening for some other reason

 

[Dsmkauai]

So did you say no oil in coolant? And I think you should try another tester just to be safe bro and before you do anything else.

 

[donniekak]

All the plugs were out and even if i didnt have WOT it should have built up to, lets say at least 150

150 is about what you'll see wot. Think about it, with the engine turning, and the throttle plate closed, the cylinders are trying to fill from a vacuum in the intake manifold. Not saying there aren't any issues with your engine. I am saying that a compression test must be ran at wot.

 

[Dsmkauai]

The Throttle Must Be Wide Open:
The reason the throttle must be wide open is to ensure that each cylinder fills completely. If the throttle is partially open, a vacuum will be generated in the inlet manifold and the pressures indicated will be lower than expected. I've always seen that it just takes longer to build up the tester, which in your case might be why the numbers are so low. Do the test again WOT and let it build for 5-7 cranks and let us know the new numbers, and remember to have the car warmed up.

 

[Calan]

Time to pull the head and upgrade something's while your in there.

How about if he figures out why his numbers are so low before just yanking the head?

OP - Try a different gauge as suggested, and make sure you are getting a good seal when you connect it to each cylinder. Check that all your timing marks line up.

If the results don't improve, do a leak-down test to help figure out what is going on.

http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

Just out of curiosity, how did you break the motor in?

 

[Dsmkauai]

^ Ya I said that because the op/he made it sound like he had coolant in his oil, maybe read more next time before posting. Anyway thx for looking out atleast bro!

Actually reading it again he did say he has coolant in his oil. I asked did anything happen before to make you check compression. He answered oil in coolant and oil coming from valve cover (new gasket and bolts tight) dip stick being forced out. So I don't think I'm wrong by suggesting getting the head off already. But yes o.p. before you rip anything off try to track down the problem 100% then go at it.

 

[BogusSVO]

One of the first things to check is the timing belt, make sure it has not jumped a tooth or two. Line up your crank marks then check the cam marks.

If the belt has jumped timing, it could allow the cams to have more overlap, causing low compression readings.

I will agree that you should try another compression tester also.

With compression numbers 70 lbs and lower, there is no way the engine would start, idle or run. By you saying that the engine was warm when the test was done, leads me to believe that you have compression of over 100 psi.

With the TB being closed will lower the reading, normally by as much as 20psi.

When you did the compression test, did you let the engine spin 3 or 4 times? or untill the gauge needle quit moving?

 

[RallyEclipse98]

I just did a compression check and I forgot to tell my brother to go WOT as he turned over the engine. The difference in the results between WOT and closed is that having the throttle closed just takes longer to get the accurate reading. At least 10 revolutions.

 

[ebb3ka94]

Well iv got a time set for tomorrow to get another test done with a different compression tester. Car runs pretty much damn perfect besides my leaking VC. PCV is fine, cleaned it out to make sure aswell. The top of the cylinders look normal, so im just a little dumb founded and worried. I road a bike for 3 months and put most my pay checks towards getting the new block put in, so to say the least this just makes me feel sick to my stomach

I just did a compression check and I forgot to tell my brother to go WOT as he turned over the engine. The difference in the results between WOT and closed is that having the throttle closed just takes longer to get the accurate reading. At least 10 revolutions.

Nice to see a Nebraskan aswell.

 

[Calan]

Actually reading it again he did say he has coolant in his oil.

After re-reading it, he actually said:

Yes, no, oil in coolant

So I have no idea what he was saying.

 

[Dsmkauai]

^^ Lol I know bro it sounds like he's saying yes and no haha, we can just ignore that ! But i think if he was answering my questions than he did say oil in coolant and oil coming from valve cover. Anyway o.p. you say your motor is fresh only 800 miles right? Who did the work? And what was your break in method? Also if you know the valve cover is leaking why not fix it already and why and were is it leaking, is it cracked? At anytime during your break in did you re torque the head studs? Let us know what the new results are after your next test am curious to see what they are.

 

[evoquon]

I am having the similar problem. I got oil in my coolant also. The car doesn't smoke and engine oil is fine. I did a compression test but I forgot to test it in wot, but I got about 120 all fours cylinders. Before I pull the head off what other possible reason oil in the coolant.

 

[1995-tsi-awd]

You can have oil in your coolant and the car can run fine... but for how long? Take off your oil cap and see if it looks milky instead of black ...it will look like chocolate milk ...if so, head gasket blown. Only a matter of time before you are blowing steam. I'd replace it now before you fun the risk of overheating it and having to re-machine the bottom end. Just my .02

 

[Calan]

Take off your oil cap and see if it looks milky instead of black ...it will look like chocolate milk ...if so, head gasket blown.

Not necessarily. Could also be a crushed oil cooler or cracked head.

 

[Dsmkauai]

Headgasket!!

 

[evoquon]

Thanks for the reply guys. I took the head off today, going to take the head to the machine shop to clean and valves job done. Hopefully this will fix the problem.

 

[bergz0]

did you have the head checked before you installed it on your new shortblock?

 

[evoquon]

did you have the head checked before you installed it on your new shortblock?

The head is still at the machine shop being work on. I just clean the gasket off the old block. Look like just a blown HG..